“…Most of the results about opioid-induced elevation of intracellular Ca 2+ come from the studies in neuronal-like cell lines (e.g., NG108-15, SK-N-SH, NMB, SH-SY5Y, Neuro2a, CHO cell lines) (Jin et al, 1992; Fields et al, 1995; Smart and Lambert, 1996; Spencer et al, 1997; Connor et al, 1997; Yoon et al, 1998, 1999; Harrison et al, 1999; Morikawa et al, 1998, 1999). Though these cells may not be identical to native brain cells, the data yielded from them provide initial clues for understanding the roles of opioid system in regulation of [Ca 2+ ]i and the relevant physiological implications (e.g., regulation of transmitter release) in early research.…”